Yawas

Yawas lets you highlight and comment web pages in multiple colors.

Your highlights are stored in the built-in Chrome Bookmarks API (you need to check Sync if you want them to be synchronized across all your devices).

Yawas automatically recreates the highlights when you reopen web pages.

All functions are available from the context-menu (Ctrl-Shift-Y for Yellow)
To highlight, simply select some text and choose the color from the context menu.
To add a note or comment, mouse over an existing highlight and pick "Add Note" (or the keyboard shortcut -N).
To recolor or delete a highlight, select some of its text and choose another color or "Delete" from the context-menu.

You can also quickly search all your bookmarks with "Yawas - Search" or edit the current page's highlights using "Yawas - Edit".